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Classic 8051 Devices

Classic 8051 devices provide on-chip RAM (bit, data, and idata), ROM (code and const), and external RAM (xdata and pdata) that your application may use.

The 8051 applications you create conform to a memory map that is dictated by the device selected and your hardware configuration. You must use the following linker directives to provide details of the memory map to the linker so it can locate program segments accordingly.

  • The CLASSES linker directive sets the address range for memory classes.
  • The SEGMENTS linker directive sets the absolute memory location for a segment, the order of segments in memory, or Special ROM (SROM) segments which execute from one address but are stored at a different address.

In addition, Code Banking applications require the BANKAREA directive to specify the memory area that contains the code banks.


  • When you use the µVision IDE, the on-chip memory areas of many devices are set automatically based on the device you select. 
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